This can be done with 2 controllers, and can be farmed fairly easily on the mission "Redstone Mines". This mission has minecarts which run along tracks throughout the level, and if they hit a player they hurt, alot. Up the difficulty to the highest you can, and walk the two players to the nearest track (you should come across one before you meet any monsters). From here, just have player two stand on the track, get hit to go down, and then player one revives. Rinse and repeat until you have the achievement.